This 23 Febrauary 2010 post from the internal NSA newsletter SIDToday describes advances in the agency’s capabilities against 4G signals, described as “a very high priority for NSA and the Intelligence Community”: see the Intercept article Operation Auroragold: How the NSA Hacks Cellphone Networks Worldwide, 4 December 2014. site-makes-first-ever-collect-of-high-interest